The concept of hiding indicia information under a SOC has been applied to numerous products, including, for example, lottery scratch-off tickets or instant games, commercial contests, telephone cards, gift cards, among many others (“scratch-off products”). Billions of scratch-off products are printed every year. Typically the indicia information (e.g., barcode, account number, win/loss information, or any other information hidden under a SOC) is the only information on a scratch-off product that is variable or different from ticket-to-ticket. For example, the variable indicia information on some scratch-off lottery tickets indicates a loss, while others indicate a free play or a win of a specified dollar amount.
The purpose of the SOC is to securely hide the indicia information of scratch-off products and ensure that the indicia cannot be read or decoded without removing the SOC. The SOC also ensures that the product has not been previously used, played, or modified. Scratch-off products also include lower security layers to ensure that the indicia cannot be read or decoded from the backside of the scratch-off product. The lower security layers, SOC and graphic display of scratch-off products are typically printed using flexography (i.e., a printing process that uses fixed plates) or gravure (i.e., a printing process that uses fixed cylindrical image carriers) due to the speed and reliability associated with printing a long run (e.g., millions of copies) of the same scratch-off product. To accommodate the high-speed fixed-plate printing process, the indicia information is typically printed using a single-color high-speed inkjet printer, with an ink-jet dye that has a substantially different chemical composition from the flexographic inks used for the layers above and below the indicia.
Individuals have developed various techniques to temporarily reveal the hidden indicia under the SOC of scratch-off products, which leave little or no trace that the scratch-off product was compromised. If the indicia can be read or decoded without removing the SOC, individuals can identify winning lottery tickets and sell only losing tickets, use telephone cards and subsequently sell them as new, and so on. Various techniques are used to temporarily reveal the hidden indicia under the SOC of scratch-off products, which leave little or no trace that the scratch-off product was compromised.
Candling is one technique that is used to reveal the hidden indicia, either from the front or backside of a scratch-off product, by using a powerful light source to overcome the security layers that provide opacity (i.e., designed to block the transmission of light). Candling techniques generally use visible wavelengths of light, but other wavelengths (e.g. infrared) may also be used. If the light source is capable of emitting light that has enough intensity to overcome the opacity of the layers above or below the indicia (i.e., enough light passes through the layers of the scratch-off product), an individual can read the indicia either directly with the naked eye or through the use of a digital camera (e.g., long exposure). This concept can be demonstrated by using a black crayon to block out text on a sheet of paper. If low intensity light is directed towards the blocked out text, the black layer will absorb nearly all of the light and the blocked out text will remain hidden. If high intensity light is directed towards the blocked out text, some of the light will be transmitted through the paper and an individual will be able to read the previously blocked out text.
Diffusion is another technique that reveals the hidden indicia under the SOC by applying a solvent (e.g., alcohol) to a scratch-off product. The solvent penetrates the upper layers of the scratch-off product and saturates the indicia dye and resin. The indicia dye is absorbed by the solvent, causing a portion of the indicia to diffuse through the upper layers of the scratch-off product, revealing a faint image of the underlying indicia. After the scratch-off product is allowed to dry, the faint image of the underlying indicia disappears from the face of the scratch-off product, leaving little to no trace that the indicia was identified via diffusion. Diffusion allows a user to generate a signal representative of the dye used for the indicia information relative to the sections of the scratch-off product surrounding the indicia—i.e., measuring a positive signal-to-noise ratio (SNR) identifying the hidden indicia without altering the SOC.
Another technique that reveals the hidden indicia under the SOC is induced fluorescence. Fluorescence is induced by supplying light of a particular wavelength that causes the indicia dye to fluoresce. The fluorescing dye emits light having wavelengths that are characteristic of the chemical composition of the dye. The different ink used for sections of the scratch-off product surrounding the indicia either emit no light or light of a different wavelength from the indicia dye. The fluorescent light emitted by the indicia dye is then captured by using a digital camera with an optical filter that only allows fluorescent light of a narrow set of wavelengths to pass through the filter. Similar to diffusion, fluorescence allows a user to measure a positive SNR identifying the hidden indicia without altering the SOC.
Another technique involves applying an electrostatic charge to a scratch-off product. Applying an electrostatic charge to the scratch-off product may induce a differential charge in the indicia dye relative to the sections of the scratch-off product surrounding the indicia. An electrophotographically printed (e.g. dry toner) indicia would be particularly susceptible to this technique, as toner is specifically designed to carry charge as an essential part of the image creation process. If an electrostatically sensitive powder (e.g., baby powder) is applied over the SOC, the powder will align in the two-dimensional shape of the indicia under the SOC. Similar to diffusion and fluorescence, the electrostatic charge allows a user to measure a positive SNR identifying the hidden indicia without altering the SOC.
Another technique for viewing the hidden indicia information is mechanically lifting the SOC using a thin blade (e.g., an X-ACTO blade) or other device to peel back a portion of the SOC to reveal the hidden indicia. The SOC is then glued back into place to conceal that the SOC was lifted to view the indicia.
Over the last few decades, the scratch-off product industry has redesigned the substrate (e.g., paper, plastic, foil, film or any other suitable material for printing scratch-off products), developed chemical barriers, and redesigned the SOC to resist known techniques for revealing the indicia. For example, the scratch-off product industry has attempted to increase the opacity of the substrate to resist candling by dying the substrate black, grey or some other color that reduces the transmission of light through the substrate (i.e., developing dark-core substrate) and increasing the thickness of the substrate to 10 mils or 254 μm.
The protect and release coat, which seals the indicia information and allows the SOC to scratch-off, has been modified to block known solvents from penetrating to the indicia. However, modifying the protect and release coat to resist known diffusion attacks often requires use of costly chemical compounds and complex curing processes involving the use of ultraviolet light or an electron beam to cure the protect and release coat in a controlled environment. Further, the protect and release coat does not protect from diffusion techniques applied to the backside of a scratch-off product. Although the layers below the indicia may also include a barrier or seal for resisting diffusion, these lower layers typically provide less protection as they must provide an adequate surface for the upper layers of the scratch-off product to adhere to. The industry has added layers above and below the indicia to block predefined wavelengths (e.g. ultraviolet and infrared) indicative of the chemical composition of the indicia.
The industry has also implemented anti-static barriers such as conductive polymer layers to resist electrostatic attempts to induce a differential charge in the indicia. The industry has also redesigned the SOC so that the coating crumbles or flakes (as opposed to peeling off in on piece), making it more difficult to conceal an attempt to mechanically lift the SOC to view the indicia.
Yet the scratch-off product industry has not identified a solution for resisting all fluorescence attacks. The inkjet dye used for the printing the indicia is composed of compounds having high molecular mass that tend to fluoresce in response to a large number of wavelengths of light (e.g., 100,000 or more wavelengths may cause fluorescence). Thus, it is nearly impossible to design barriers that block every possible wavelength that can cause fluorescence in the indicia dye. Additionally, minute variations in the chemical composition of the indicia dye, which do not affect the appearance of the indicia and are considered acceptable for printing, may greatly alter the fluorescence characteristics of the indicia dye. Accordingly, wavelengths of light that did not cause fluorescence in previously tested indicia dye may result in fluorescence due to the minute variations in the chemical composition of the indicia dye. Even if reliable blocking layers are engineered to block nearly all wavelengths of light, digital cameras using long timed exposures and appropriately tuned narrow-band optical filters are capable of capturing minute emissions of fluorescence from the indicia dye, revealing the hidden indicia information.
The scratch-off product industry also continues to be challenged to address the problem of assisted mechanical lifts to view hidden indicia under the SOC. Assisted mechanical lifts involve applying a material to the SOC (e.g., clear acrylic coating) that strengthens the SOC and resists crumbling or flaking when a user attempts to mechanically lift the SOC. That means users can more easily glue the SOC back into place, concealing the mechanical lift.
Further, scratch-off products are still printed using indicia dye that has a different chemical composition from the inks used for the layers above and below the indicia. Because many of the various techniques for identifying hidden indicia information of a scratch-off product rely on the indicia dye having a different chemical composition from the inks used for the layers above and below the indicia, the possibility still remains that new techniques may be developed in the future for inducing diffusion, fluorescence, electrostatic charge, or some other characteristic feature to identify hidden indicia information.
The scratch-off product industry also continues to be challenged to develop an efficient printing process that addresses the problem of candling without impacting the aesthetics of scratch-off products. One technique for resisting candling involves the use of foil-laminated substrates to provide opacity for scratch-off products (see e.g., U.S. Pat. No. 4,540,628 to Koza et al.). Although the use of foil-laminated substrate is not susceptible to delamination (i.e., peeling off the foil laminate from the substrate would still protect the overlying indicia) and resists candling (i.e., bright light is reflected by foil), the opacity is provided by thick foil and various layers of varnish, which is not recyclable.
Another technique involves the use of dark-core substrates (see e.g., U.S. Pat. No. 5,213,664 of Hansell and U.S. Pat. No. 6,340,517 of Propst). Unlike foil-laminated substrate, dark-core substrate is recyclable because it does not contain metal. However, dark-core substrate relies on the thickness of the substrate for opacity and can easily be delaminated (i.e., the substrate can be soaked in liquid and peeled into two thinner halves each of which has significantly less opacity than the original substrate) to view the hidden indicia via candling. The substrate could then be glued back together to conceal the delamination.
The scratch-off product industry also applied thin metalized ink film directly to the substrate via flexographic or gravure printing (see e.g., U.S. Pat. No. 5,532,046 of Rich et al.). Although the thinner metalized ink film is more environmentally friendly than foil-laminated substrate, it does not provide sufficient opacity to protect against candling.
In the late 1990s, the scratch-off product industry developed security layers comprised of black and white ink film coatings that could be printed using flexographic plates and/or gravure cylinders. These security layers replaced the use of dark-core substrates and foil-laminated stock as they were not susceptible to delamination and provided adequate protection against candling. However, the addition of lower-security layers has resulted in elaborate press configurations that require significant testing and verification to setup a press run of a scratch-off product. For example, printing a scratch-off product may require using up to 29 different flexographic plates for each color separation or sub-layer. Eight of the plates are typically used for printing the upper and lower opacity layers (2 layers of black each) and upper and lower background layers (2 layers of white each).
Printing lower security layers on the substrate also impacts the aesthetics of scratch-off products. Because the upper and lower opacity layers are comprised of dark colors, the white background layers are unable to fully mask the color black, resulting in a tinted grey surface that may also have a rough surface texture that distorts the overlaid graphics of the scratch-off product. If colorful images are printed on the upper or lower background layers, the resulting grey surface distorts the colors causing the colors to appear dull. Some scratch-off products use additional background layers to brighten the background, however, the cost of additional white layers is significant and adds to the complexity of the press configuration for printing a scratch-off product.
Further, the level of opacity provided by the security features of a scratch-off product are not well-defined within the industry. For example, the scratch-off product industry uses trial and error and likely excessive amounts of colorant to achieve some undefined level of “total opacity” (see e.g., U.S. Pat. No. 5,213,664 of Hansell) rather than defining a range of acceptable opacities and designing the opacity coating to meet the defined opacity. The term “total opacity” does not define any particular opacity, as the measurement of opacity (i.e., the ability of a material to block the transmission of light) is a function of the intensity of light provided by a light source. A material that has an opacity of 99.9 percent (i.e., transmittance of 0.001) may be measured to have 100 percent opacity (i.e., zero transmittance) if the intensity of the light source is so low that the transmitted light signal is too small to detect.
Due to the lack of better techniques for resisting delamination, candling, fluorescence, electrostatic charge, and assisted/unassisted mechanical lifts, security ink film coatings and indicia dye that has a different chemical composition from the inks used for the layers above and below the indicia remain in wide usage for the production of scratch-off products. Further, the inability to design security coatings to meet defined opacities results in significant added cost and wasted materials in the production of scratch-off products. Accordingly, there is an unmet demand for a method of efficiently printing scratch-off products that effectively resists known and unknown techniques for revealing the hidden indicia information and allows for improvements to the aesthetic design of scratch-off products.